Seasonal dynamic changes of sapwood and heartwood in larix gmelinii
This study describes the seasonal dynamic changes of heartwood transformation of Larix gmelinii by establishing the relationship between trunk radius, heartwood radius, sapwood width, trunk growth rings and heartwood growth rings in different heights during the growth season with regression analysis. The results showed that the initial age of heartwood formation was 7.25 years. Heartwood began to form when the trunk radius was greater than 2.6 cm, and then the heartwood radius grew 0.85 cm for every 1.00 cm growth of the trunk radius. It was also demonstrated that the significant change and growth rate of heartwood with month were higher than sapwood at the tree base and 1 m height, but lower than sapwood at 5 m and 9 m height. The absolute content of heartwood and sapwood area decreased with tree height, however, the relative content of sapwood area increased with the tree height.